1. Field of the Invention
This invention concerns a method and apparatus for forming frames and framework inter alia for panelling, shelving, sales displays, shopfitting, plinths, enclosures, point of sale aids, structures for exhibitions, mirrors, stage sets, photoframing, signage, extensions to buildings and frames for filters. When the invention is used as an edging then paper, card, artboard, building board, sheet plastic, sheet metal, expanded metal and glass are all suitable.
2. Description of the Prior Art
Mitred frames in softwood and aluminium are widely employed for picture and photoframing. A mitre joint requires precision in marking out, execution and subsequent assembly and any discrepancy is at once apparent. A mitre joint is usually butted and consequently needs a support structure. Half lap mitres are only feasible in timber. Otherwise the butted frame must be fixed from the rear to a stable usually plain-lapped rectangular frame and all high class framing use this technique.
The latter construction is no use for metal frames. The mitred parts are instead grooved continuously around the outer edge and four machined L-aluminium corner braces are screwed into the groove with self tapping screws. Adaptation for display work involves releasing two corners, sliding into the groove a pair of tube embracing plastic grips, refitting both corners and snapping the grips onto the tube.
Boards such as artboard bearing pictures can be mounted in channel section plastic extrusions which are joined along the longitudinal edge by an integral hinge line. This allows two flat displays to stand say at 90 degrees but there is no means for ensuring that the extrusion maintains a tidy continuous border around the work.